Module org.jhotdraw8.graph

Package org.jhotdraw8.graph.path.algo

Class AllWalksSpliterator<V,A,C extends Number & Comparable<C>,E>

java.lang.Object

java.util.Spliterators.AbstractSpliterator<OrderedPair<ImmutableList<E>,C>>

org.jhotdraw8.collection.enumerator.AbstractEnumerator<OrderedPair<ImmutableList<E>,C>>

org.jhotdraw8.graph.path.algo.AllWalksSpliterator<V,A,C,E>

Type Parameters:

V - the vertex data type

A - the arrow data type

C - the cost number type

E - the element type of the path

All Implemented Interfaces:

Spliterator<OrderedPair<ImmutableList<E>,C>>, BareEnumerator<OrderedPair<ImmutableList<E>,C>>, Enumerator<OrderedPair<ImmutableList<E>,C>>

public class AllWalksSpliterator<V,A,C extends Number & Comparable<C>,E>
extends AbstractEnumerator<OrderedPair<ImmutableList<E>,C>>

Iterates over all walks from a set of start vertices to a set of goal vertices using a breadth-first search.

Only enumerates walks that contain a goal once.

Expected run time: The enumeration of all walks in a graph is NP-complete. (Because counting paths is #P-complete).

Only run this algorithm on acyclic graphs. In graphs with cycles the algorithm may run out of space, and will then throw a IllegalStateException. In an acyclic graph, the algorithm will return paths (a path is a walk that only contains each vertex once).

References:

Leslie G. Valiant. (1979)

The Complexity of Enumeration and Reliability Problems. Chapter 4. Some #P-complete problems. Item 11. S-T CONNECTEDNESS math.cmu.edu

Nested Class Summary

Nested classes/interfaces inherited from interface org.jhotdraw8.collection.enumerator.Enumerator

Enumerator.OfDouble, Enumerator.OfInt, Enumerator.OfLong

Nested classes/interfaces inherited from interface java.util.Spliterator

Spliterator.OfDouble, Spliterator.OfInt, Spliterator.OfLong, Spliterator.OfPrimitive<T,T_CONS,T_SPLITR extends Spliterator.OfPrimitive<T,T_CONS,T_SPLITR>>

Field Summary

Fields inherited from class org.jhotdraw8.collection.enumerator.AbstractEnumerator

current

Fields inherited from interface java.util.Spliterator

CONCURRENT, DISTINCT, IMMUTABLE, NONNULL, ORDERED, SIZED, SORTED, SUBSIZED

Constructor Summary

Constructors

Constructor	Description
AllWalksSpliterator(@NonNull Iterable<V> startVertices, @NonNull Predicate<V> goalPredicate, @NonNull Function<V,Iterable<Arc<V,A>>> nextArcsFunction, @NonNull Function<ArcBackLinkWithCost<V,A,C>,OrderedPair<ImmutableList<E>,C>> sequenceFunction, int maxDepth, @NonNull C maxCost, @NonNull C zero, @NonNull Function3<V,V,A,C> costFunction, @NonNull BiFunction<C,C,C> sumFunction)	Creates a new instance.

Method Summary

Modifier and Type	Method	Description
boolean	moveNext()

Methods inherited from class org.jhotdraw8.collection.enumerator.AbstractEnumerator

current

Methods inherited from class java.util.Spliterators.AbstractSpliterator

characteristics, estimateSize, trySplit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.jhotdraw8.collection.enumerator.Enumerator

tryAdvance

Methods inherited from interface java.util.Spliterator

characteristics, estimateSize, forEachRemaining, getComparator, getExactSizeIfKnown, hasCharacteristics, trySplit

Constructor Details

AllWalksSpliterator

public AllWalksSpliterator(@NonNull Iterable<V> startVertices,
 @NonNull Predicate<V> goalPredicate,
 @NonNull Function<V,Iterable<Arc<V,A>>> nextArcsFunction,
 @NonNull Function<ArcBackLinkWithCost<V,A,C>,OrderedPair<ImmutableList<E>,C>> sequenceFunction,
 int maxDepth,
 @NonNull C maxCost,
 @NonNull C zero,
 @NonNull Function3<V,V,A,C> costFunction,
 @NonNull BiFunction<C,C,C> sumFunction)

Creates a new instance.

Parameters:

startVertices - the set of start vertices

goalPredicate - the goal predicate

nextArcsFunction - the next arcs function

sequenceFunction - the function that maps back links to a sequence

maxDepth - the maximal depth (inclusive) of the search Must be >= 0.

maxCost - the maximal cost (inclusive) of a sequence Must be >= zero.

zero - the zero cost value

costFunction - the cost function.

sumFunction - the function for adding two cost values

Method Details

moveNext

public boolean moveNext()

Returns:

true on success

Throws:

IllegalStateException - if the underlying queue runs out of space